Piston ring



Nov. 6, 1928. 1,690,423 Y A. J. MUMMERT PIsTN RING Filed oct. 9, 1926 f7 ave/7 (fb/,v Afa/77 e/Z/ Patented Nov. 6, 1928.

AUNITED STATES PATENT ori-ica ABDEN JOHN MUMEERT, 0F UNIVERSITY CITY, MISSOURI, ASSIGNOR TOv MCQUAY- NOBBIS MANUFACTURING COMPANY, ST, LOUIS, MISSOURI, A. vCORI.0R.A.'1I0N' 0F DELAWARE rrsToN RiNG.

Application filed October 9, 1926 Serial No. 140,625.

My invention relates to piston rings and more particularly to piston rings adapted for use in internal combustion engines and formed and arranged so as to be compressible axially whereby a tight fit may be had between the side faces of the piston ring and the side walls of the groove in the piston in which the ring is mounted so that leakagey rearwardly around the piston ring will prevented.

Heretofore pistonI rings have been provided with two or more circumferentlally disposed rows of slots with the slots in one row staggered in relation to the slots inthe adjacent row so that to some. extent the ring'I may beaxially compressed to bring the side faces closer together, but in manufacturing piston rings of this type many obstacles have been met. A reat number of piston rings used in automo iles today are mounted on the small pistons of internal combustion enginesV having a comparativelygreat number of cylinders of small bore and the ypiston rings which are necessarily of small diameter are usually of-narrow width. vIf two rows of slots are cut in such a piston ring in which the width of the cylinder contactl ing face is small it has ybeen found that if the rows of slots are positioned far enough away from the side faces of the ring to leave substantially wide side annular portions to' give the ring enough rigidity, the central annulai` portion left between the two rows of slots will be so narrow as to be easily broken-and as to not \give the side faces of the ring enough pressure against the sidewalls of the ring groove in the piston. In turn, if the two rows of slots are. separated enough, to leave a central annular portion therebetween of sufficient width to prevent itsbeing bro` ken in use'and to give suiiicie'nt pressure of the side faces of the piston ring against the side walls of the ring groove, the result will be that the side annular portions between a row of slots and the adjacent side faces of the ring will be so narrow as to be easily broken-even in handling and shipping. The object of my invention is to provide a piston ring with slots therein so formed' the ring betweena row of slots and the side face adjacent thereto of such formation'as to be strong enough to withstand the shocks of shipping and of use in an internal combustion engine. y

With these and other objects in view one form of piston ring embodying my invention is fully shown in the accompanying drawings wherein similar characters are used to designate similar parts: F ig.l 1 is a View of a piston ring developed so as to show the whole outer circumference thereof; Fig. 2 is a perspective of the piston ring in its natural shape; Fig. 3 is a section along the lines 3 3 in F ig. 1 with the piston ringv mounted in the piston ring lgroove of a piston. 1

In this embodiment of my invention the piston ring consists of a one-piece, resilient split band l provided with a step-cut joint 2. A plurality of slots 3 shaped as hereinafter described are arranged in circumferentially disposed rows as shown in Fig.-1 with the slots in one row staggered in re -lation to the slots in the other row. Preferably one of the slot-s extendsacrossthe joint 2, as shown, to malte the portions of the ring adjacent the joint co'mpressible.

Vlien the slots are arranged in two rows as shown in the figures the piston ring will have a central annular portion 5 positioned between the rows of slots and side annular portions 6 positioned between a row of slots and Athe adjacent side face of the piston ring.v Each of the slots 3 has theinner Wall 8 thereof, that is, the wall nearest the other row of slots, substantially fiat and substan` ,tially parallehwith the side faces Z,and, therefore, thefinner walls 8 of the slots in one row of s'lotswill be substantially parallel to the ini'ienwalls of the slots in the other row andthe sidesfof the central annular portion will be substantially parallel. The outer wall 9 of eachlof the slots 3, that is, the wall of the slot adjacent` the nearest side face of the piston ring, is,`preferably,

substantially arcuate in shape and mergesif,

and` arranged 'as to "form a 4cent-ral annular sbodying my invention I prefer to use a portion of suiiicient Width to give theproper pressure of the side faces of the ring against the side walls ofd the ring oove inl the piston and to form outerfannu ar portions of small cutter having teeth tapering from topk to bottom towards 'the outer edge thereof and if such a cutter is used to cut from the outer to the inner wall of the ring, the outer wall 9 will slope slightly downwardly from the front face of the piston ring to the rear face thereof, as shown in l. Therefore, the opening of the slot on the rear face of the piston ring will be slightly shorter than the opening of the slot on the cylinder contacting face.

If the outer walls 9 of the slots 3 are arranged as shown to merge into the flat inner wall 8 the side annular portions 6 will be formed of a plurality of integral arched spans each extending between the bodies of metal left between the adjacent slots in a row. When the side annular portions are formed in this manner they will be rigid and strong. Likewise, if the slots are arranged as shown the central annular portion 5 will be substantially uniform in thickness throughout the whole circumference of the ring and, therefore, the pressure of the' side faces t against the side Walls of the piston ring groove ll in the piston 4 Will be uniform throughout the length of the piston ring. Moreover, the shape vof these slots will not affect the axial eompressibility of the piston ring and when the piston ring is compressed in the piston ring groove the inner Walls 8 of the slots will be somewhat bowed outwardly and will be more nearly parallel with the outer walls 9.

It may be readily understood that embodiments of my invention may be varied within wide limits and details of construction may be changed Without deviating from the spirit of my invention as embodied in the claims: set forth below.

What I claim as new and desire to secure by Letters Patent, is

1. An axially eompressible piston ring comprising a` resilient split band having two circumferentially disposed rows of slots with the slots in one row staggered in relation to the slots in the other row, and

said slots having the outer walls thereof substantially arcuate in shape and havin;r the inner Walls of the slots in one row suhstantially parallel to the inner Walls of the slots in the other row.

2. An axially eompressible piston ring comprising a resilient split band having two circumferentially disposed rows of slots with the slots in one row staggered in relation lo the slots in the other row, and said slos having one wall thereofsubstantially flat and substantially parallel with a side face of said ring and having the other wall thereof merging at its ends into said flat Wall.

3. An axially compressihle pistonV ring comprising a resilient split band having two circumferentially disposed rows of slots with the slots in one row staggered in relation to the slots in the other row, and each of said slots having the inner wall thereof substantially flat and parallel to a side face of said ring and having the outer wall thereof arcuate in shape and merging at its ends into said inner wall.

4. An axially eoinpressible piston ringr comprising a resilient split band having two cireuiut'erentially disposed rows of slots with the slots in one row staggered in relation to the slots in the other row, and each of said slots having the .outer wall thereof sub stantially arcuate in shape whereby the annular portion of the ring between a row ol' slots and the adjacent side face of the ringr is formed of a pluralityl of integral arched spans each extending between the bodies of metal left between the ends of adjacent slots in the row and the inner walls of the slots in onel row being substantially parallel to the inner walls of the slots in the other row.

l'n witness whereof I have signed my name to the foregoing specilieation.

ARDEN JOHN MUMMERT. 

